// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// This file contains an implementation of a VP8 raw stream parser,
// as defined in RFC 6386.

#ifndef MEDIA_FILTERS_VP8_PARSER_H_
#define MEDIA_FILTERS_VP8_PARSER_H_

#include <stddef.h>
#include <stdint.h>

#include "base/macros.h"
#include "media/base/media_export.h"
#include "media/filters/vp8_bool_decoder.h"

namespace media {

// See spec for definitions of values/fields.
const size_t kMaxMBSegments = 4;
const size_t kNumMBFeatureTreeProbs = 3;

// Member of Vp8FrameHeader and will be 0-initialized
// in Vp8FrameHeader's constructor.
struct MEDIA_EXPORT Vp8SegmentationHeader {
    enum SegmentFeatureMode { FEATURE_MODE_DELTA = 0,
        FEATURE_MODE_ABSOLUTE = 1 };

    bool segmentation_enabled;
    bool update_mb_segmentation_map;
    bool update_segment_feature_data;
    SegmentFeatureMode segment_feature_mode;

    int8_t quantizer_update_value[kMaxMBSegments];
    int8_t lf_update_value[kMaxMBSegments];
    static const int kDefaultSegmentProb = 255;
    uint8_t segment_prob[kNumMBFeatureTreeProbs];
};

const size_t kNumBlockContexts = 4;

// Member of Vp8FrameHeader and will be 0-initialized
// in Vp8FrameHeader's constructor.
struct MEDIA_EXPORT Vp8LoopFilterHeader {
    enum Type { LOOP_FILTER_TYPE_NORMAL = 0,
        LOOP_FILTER_TYPE_SIMPLE = 1 };
    Type type;
    uint8_t level;
    uint8_t sharpness_level;
    bool loop_filter_adj_enable;
    bool mode_ref_lf_delta_update;

    int8_t ref_frame_delta[kNumBlockContexts];
    int8_t mb_mode_delta[kNumBlockContexts];
};

// Member of Vp8FrameHeader and will be 0-initialized
// in Vp8FrameHeader's constructor.
struct MEDIA_EXPORT Vp8QuantizationHeader {
    uint8_t y_ac_qi;
    int8_t y_dc_delta;
    int8_t y2_dc_delta;
    int8_t y2_ac_delta;
    int8_t uv_dc_delta;
    int8_t uv_ac_delta;
};

const size_t kNumBlockTypes = 4;
const size_t kNumCoeffBands = 8;
const size_t kNumPrevCoeffContexts = 3;
const size_t kNumEntropyNodes = 11;

const size_t kNumMVContexts = 2;
const size_t kNumMVProbs = 19;

const size_t kNumYModeProbs = 4;
const size_t kNumUVModeProbs = 3;

// Member of Vp8FrameHeader and will be 0-initialized
// in Vp8FrameHeader's constructor.
struct Vp8EntropyHeader {
    uint8_t coeff_probs[kNumBlockTypes][kNumCoeffBands][kNumPrevCoeffContexts]
                       [kNumEntropyNodes];

    uint8_t y_mode_probs[kNumYModeProbs];
    uint8_t uv_mode_probs[kNumUVModeProbs];

    uint8_t mv_probs[kNumMVContexts][kNumMVProbs];
};

const size_t kMaxDCTPartitions = 8;

struct MEDIA_EXPORT Vp8FrameHeader {
    Vp8FrameHeader();

    enum FrameType { KEYFRAME = 0,
        INTERFRAME = 1 };
    bool IsKeyframe() const { return key_frame == KEYFRAME; }

    enum GoldenRefreshMode {
        COPY_LAST_TO_GOLDEN = 1,
        COPY_ALT_TO_GOLDEN = 2,
    };

    enum AltRefreshMode {
        COPY_LAST_TO_ALT = 1,
        COPY_GOLDEN_TO_ALT = 2,
    };

    FrameType key_frame;
    uint8_t version;
    bool is_experimental;
    bool show_frame;
    size_t first_part_size;

    uint16_t width;
    uint8_t horizontal_scale;
    uint16_t height;
    uint8_t vertical_scale;

    Vp8SegmentationHeader segmentation_hdr;
    Vp8LoopFilterHeader loopfilter_hdr;
    Vp8QuantizationHeader quantization_hdr;

    size_t num_of_dct_partitions;

    Vp8EntropyHeader entropy_hdr;

    bool refresh_entropy_probs;
    bool refresh_golden_frame;
    bool refresh_alternate_frame;
    GoldenRefreshMode copy_buffer_to_golden;
    AltRefreshMode copy_buffer_to_alternate;
    uint8_t sign_bias_golden;
    uint8_t sign_bias_alternate;
    bool refresh_last;

    bool mb_no_skip_coeff;
    uint8_t prob_skip_false;
    uint8_t prob_intra;
    uint8_t prob_last;
    uint8_t prob_gf;

    const uint8_t* data;
    size_t frame_size;

    size_t dct_partition_sizes[kMaxDCTPartitions];
    // Offset in bytes from data.
    off_t first_part_offset;
    // Offset in bits from first_part_offset.
    off_t macroblock_bit_offset;

    // Bool decoder state
    uint8_t bool_dec_range;
    uint8_t bool_dec_value;
    uint8_t bool_dec_count;
};

// A parser for raw VP8 streams as specified in RFC 6386.
class MEDIA_EXPORT Vp8Parser {
public:
    Vp8Parser();
    ~Vp8Parser();

    // Try to parse exactly one VP8 frame starting at |ptr| and of size |size|,
    // filling the parsed data in |fhdr|. Return true on success.
    // Size has to be exactly the size of the frame and coming from the caller,
    // who needs to acquire it from elsewhere (normally from a container).
    bool ParseFrame(const uint8_t* ptr, size_t size, Vp8FrameHeader* fhdr);

private:
    bool ParseFrameTag(Vp8FrameHeader* fhdr);
    bool ParseFrameHeader(Vp8FrameHeader* fhdr);

    bool ParseSegmentationHeader(bool keyframe);
    bool ParseLoopFilterHeader(bool keyframe);
    bool ParseQuantizationHeader(Vp8QuantizationHeader* qhdr);
    bool ParseTokenProbs(Vp8EntropyHeader* ehdr, bool update_curr_probs);
    bool ParseIntraProbs(Vp8EntropyHeader* ehdr,
        bool update_curr_probs,
        bool keyframe);
    bool ParseMVProbs(Vp8EntropyHeader* ehdr, bool update_curr_probs);
    bool ParsePartitions(Vp8FrameHeader* fhdr);
    void ResetProbs();

    // These persist across calls to ParseFrame() and may be used and/or updated
    // for subsequent frames if the stream instructs us to do so.
    Vp8SegmentationHeader curr_segmentation_hdr_;
    Vp8LoopFilterHeader curr_loopfilter_hdr_;
    Vp8EntropyHeader curr_entropy_hdr_;

    const uint8_t* stream_;
    size_t bytes_left_;
    Vp8BoolDecoder bd_;

    DISALLOW_COPY_AND_ASSIGN(Vp8Parser);
};

} // namespace media

#endif // MEDIA_FILTERS_VP8_PARSER_H_
